Prof. Steve Nerem
Colorado Center for Astrodynamics Research (CCAR), University of Colorado, Boulder (CO)
Over the last 25 years, data from TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 have been used to observe changes in global mean sea level. A rate of rise of 3.4 ± 0.4 mm/year has been observed. However, observing a possible acceleration in the rate of sea level rise is more challenging and pushes the limits of the observing system accuracy. This presentation will examine the feasibility of detecting an acceleration in the altimeter sea level record. First, the available evidence for estimating how big of an acceleration might be expected in the altimeter record will be reviewed.
Next, the errors in the altimetry will be discussed in the context of tide gauge validation of the altimeter record. The role of interannual variability in GMSL in measuring the acceleration will be addressed. The role of decadal variability and how it might influence the determination of acceleration, including the role that the 1991 eruption of Mount Pinatubo might have had on the altimeter sea level record, will be discussed. Finally, progress towards understanding the acceleration of GMSL over the 25-year record, based on consideration of all of these issues, including the importance of using the tide gauge validation to understand the errors in the acceleration estimate, will be discussed.